Such a device is for example known from patent document EP 0,995,976 entitled “Metering end cap and container equipped with a metering end cap according to the invention”. The device described in this document has a large number of molded or blown parts, the manufacturing and assembly tolerances of which are very low. Moreover, the design of this device requires guiding the valve, called “metering piston”, both on its internal diameter and on its external diameter, which causes the generation of high friction forces.
U.S. Pat. No. 4,582,230, entitled “Metering Device”, also describes a fluid metering device, this metering device implementing a lock of which volume corresponds to the unitary metered amount. The outlet aperture of the metering device is selectively shut-off by a piston connected by a cylindrical rod to a ball controlling the opening of the lock, on the upstream space side delimited by a bottle. When the bottle is held in a vertical position, the piston closes the pourer of the metering device. When the bottle is being overturned, the piston keeps on maintaining the pourer closed, while the liquid enters in the lock. Once the bottle is in the vertical position, the ball closes the inlet of the lock, whereas the piston is descended, opening the pourer and releasing the liquid contained in the lock.
In addition to the fact that this solution also requires implementing a large number of parts, the result sought can only be obtained by slowly reversing the bottle, so that the tank fills in before the ball comes to close the liquid inlet in the tank, and before the piston releases the liquid contained in the tank. In addition, such a device is not adapted to the metering of viscous fluids.